66 REPORT—1849. 
Of chloride of sodium two solutions were examined, the first containing 
29215, the second 14°607 chloride of sodium for 100 water. The air was 
nearly steady between 17°9 and 18°. 
Solution I. Water. Solution II, Water. 
5107 4111 4740) 4111 
5127 4106 4733 4106 
5128 4731 
Mean.... 5121 4108 4735 4108 
i Il. 
Specific heat............ 08018 0°8671 
Specific gravity........... 1°1724 1-0942 
It may be not uninteresting to compare these numbers with those deduced 
by calculation from the specific heats of the salts in the dry state. The latter 
have been nade the subject of experiment by Avogadro and Regnault, but 
their results do not agree well with each other. I have adopted Regnault’s 
- numbers in my calculations. 
Solution. Specific heat Mean spec. heat of 
by experiment. dry salt and water. 
Nitrate of potash 1 0°8135 0°8463 
» ” 2 0°8915 09145 
> . 33 3s 0°9369 0'9566 
Nitrate of soda l. 0°7838 0°7847 
x > 2. 0°8585 0°8736 
a » 4}; 09131 0:9307 
Chloride of sodium 1. 0°8018 0°8224: 
os “6 Zs 0°8671 0°9000 
It is obvious that the specific heat of the solution is, in every instance, less 
than the mean of the specific heats of its component parts, and that serious 
errors would be committed, if we should attempt to calculate on this principle 
of the thermal values of solutions which may be formed in the course of our 
experiments. 
I have made a short series of experiments on the quantities of heat 
absorbed during the solution of nitrate of soda and of nitrate of potash, when 
added in successive portions to the same liquid. The results fully confirm 
those previously obtained by Graham, but as the experiments were only pre- 
liminary trials to a more extended investigation, it is not necessary to describe 
them in detail. I may briefly state, that on dissolving 12-22 grammes of ni- — 
trate of soda in 250 grammes of water and repeating the experiment with 
each new solution, till the water was nearly saturated, the following decre- 
ments of temperature were found :— 
1. 280C 6. 1é60C. 
2. 243 7 AT 
eer 8- 1:39 
4. PM«gQ SP) pas 
5. 
By the aid of the specific heats already determined, and knowing the thermal 
value of the vessel in which the experiments were performed (4°3 grms.), I 
have calculated for experiments 1, 4 and 9 the following numbers, which ex- 
: i 
Pi 
_ 
~J 
ion 
_ 
j=) 
— 
bb 
~J 
Vie Sms Rasa iat 

